CXCL9 and COVID-19: The ongoing inflammatory response after acute COVID-19 remission keeps the expression of proinflammatory cytokines such as IFN-β, IFN-λ1, IFN-γ, IL-2, IL-6, IL-17, CXCL8, CXCL9, and CXC10 upregulated, the activation of non-classical and intermediate monocytes, fibroblasts, and myeloid cells [40].